Direct Laser Writing Polymer Micro-Resonators for Refractive Index Sensors

摘要

A sensitive refractometric polymer micro-resonator sensor is fabricated using direct laser writing. The design consists of two tapered waveguides that can be directly coupled by single mode fibers, two “Y” splitting waveguides that are combined in a Mach-Zehnder interferometer (MZI) configuration and a micro-cylinder that evanescently couples with the arms of the MZI. The resonant wavelength shifts in response to the refractive index change in the surrounding medium of the micro-cylinder. The strong interaction between the medium and the whispering gallery mode results in a sensitivity of 154.84 nm/RIU (refractive index units), which demonstrates that such micro-resonators can be used for measurements of refractive index of liquids.